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Hingeless flow control over an airfoil via distributed actuationAgrawal, Anmol 25 April 2007 (has links)
An experimental investigation was undertaken to test the effectiveness of a novel design
for controlling the aerodynamics of an airfoil. A synthetic jet actuator (SJA) was placed
inside a NACA 0015 airfoil with its jet at 12.5% of the chord length, hereby referred to
as the leading edge actuator. Four centrifugal fans across the span were mounted at 70%
of the chord and the jet formed by them was located at 99% of the chord, hereby referred
to as the trailing edge actuator. The effects of these actuators on the aerodynamic
properties were studied, separately and then in conjunction, with varying angles of
attack.
The leading edge actuator delays the onset of stall up to 24 degrees, the maximum angle
of attack that could be attained. The control of the aerodynamics was achieved by
controlling the amount of separated region. There was no effect of the actuation at lower
angles of attack.
The trailing edge actuator provides aerodynamic control at both low and high angles of
attack. The study investigated the effect of jet momentum coefficient on the aerodynamic properties for various angles of attack. The data obtained shows that lift
control (in both positive and negative direction) was achieved even at low angles. The
actuator enhances the aerodynamic properties by changing the pressure distribution as
well as by delaying flow separation.
Study of the combined actuation shows that the synthetic jet actuator was very effective
in delaying stall when the trailing edge jet was ejected from the upper surface. For the
case when the jet is ejected from the lower surface, there is less control. This can be
accounted for by the difference in aerodynamic loading for both cases.
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